1. Technical Field of the Invention
The present invention relates to a telecommunications network and, in particular, to the provision of a roaming independent dialing procedure for accessing a long distance carrier within a mobile telecommunications network.
2. Description of Related Art
Whenever a mobile station travels into a new Mobile Switching Center (MSC) coverage area or a subscriber turns on his or her mobile station for the first time, the mobile station attempts to register with the serving MSC by transmitting an associated identification number known as the International Mobile Subscriber Identity (IMSI) number. The serving MSC then communicates with a particular home location register (HLR) associated with the mobile station using the received IMSI number. This communication is to inform the HLR of the mobile station's new location and to retrieve requisite subscriber information from the HLR to provide mobile service to the newly registering mobile station. As a result, because of such a "roaming" arrangement and location update procedures, a mobile station is able to freely access mobile service through a number of different MSCs not only within its home Public Land Mobile Network (PLMN), but also within a visiting PLMN.
With the introduction of inter-network compatibility and protocol interfaces within a mobile telecommunications environment, such as the Global System for Mobile (GSM) and Personal Communications System (PCS) telecommunications standards, a mobile station is not only able to travel (roam) between a first PLMN and a second PLMN, but also between a first PLMN within a first country and a second PLMN within a second country. Especially in Europe, a mobile subscriber is able to travel across a number of different European countries supporting the GSM standard and receive incoming calls and originate outgoing calls using the same mobile station.
Additionally, utilizing the above described mobile telecommunications network, mobile subscribers are provided with a number of advanced subscriber features and services. One such service enables a mobile subscriber to specify his or her preferred long distance carrier while making long-distance calls. As an illustration, a mobile subscriber specifies a particular long distance carrier by dialing an access code associated with that long distance carrier, such as *10288 for AT&T. After receiving a confirmation from AT&T, the mobile subscriber then dials his or her destination B-number. A long distance call connection is thereafter established by AT&T and the mobile subscriber is charged in accordance with his or her subscription agreement with AT&T. As a result, independent of the geographic area, mobile telecommunications network, and the mobile station, mobile subscribers are able to specify and utilize their preferred long distance carriers.
Because each PLMN, or more specifically each country, has its own dialing plans, an access code for establishing a call connection with a desired long distance carrier differs from one geographic location to another. For example, within the United States, the access code *10288 might represent AT&T. In South America, such as Mexico, *12233 or another E.164 formatted directory number might instead represent AT&T. Because of such differences, a mobile subscriber roaming between a number of different networks or countries needs to inconveniently maintain an appropriate list identifying the correct access code associated with each network, and then manually dial the proper access code. Such inconveniences are further aggravated by the fact that the mobile subscriber may not even know the access number for his or her long distance carrier within the current network.
Accordingly, there is a need for a mechanism to provide a location independent access code dialing procedure within a mobile telecommunications network.